Mixing is a process in which two or more substances are combined while the chemical properties of each substance remain unchanged. The properties of the overall mixture, however, can differ from those of the component substances. Thus, mixing is often used to produce a medium with a desired set of physical and chemical properties.
For example, in semiconductor fabrication, chemical mechanical planarization (CMP) is used to make wafer surfaces flat. This process requires slurry of abrasive particles dispersed in a chemically corrosive agent. During CMP, movement of the abrasive particles on the wafer mechanically removes material from the wafer surface. The chemically corrosive agent of the slurry facilitates this mechanical removal of material by reacting with the material to be removed. To produce CMP slurry having desired properties, it can be useful to filter the CMP slurry to achieve the desired distribution of abrasive particles dispersed within the chemically corrosive agent.